In process control systems, particularly those that involve one or more chemical processes, it is often desirable to utilize and track the behavior of some form of catalyst—i.e., a substance that initiates, accelerates, reduces the activation energy of, or otherwise assists in a chemical reaction while not taking part in that reaction as a product or reactant. Depending upon the nature of the process itself, such catalysts typically include, for example, transition metals, transition metal oxides, aluminum oxides, organic enzymes, and the like.
The behavior of a process that utilizes a catalyst is highly dependent upon the properties of that catalyst (e.g., catalyst activity, catalyst age, metal content), and thus it is desirable to understand the state of the catalyst for the purpose of, for example, predicting process yield. Unfortunately, it is very difficult to estimate the properties of a catalyst in situ.
Because a catalyst is usually a set of particles, a particular catalyst property is best represented as a distribution, rather than a single value. Furthermore, many different factors influence catalyst properties—including such mechanisms as thermal deactivation, metal poisoning, regeneration effectiveness, and catalyst makeup rate. While laboratory analysis may be performed on catalyst samples extracted from the process, such analyses can be time-consuming, unreliable, and expensive.
Accordingly, it is desirable to provide more reliable, timely, and inexpensive methods of estimating catalyst properties in a process control system. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.